Yeast lysis during bottle-fermented sparkling wines ageing in presence of a beta-glucanase oenological
Author(s)
Torresi, Sara
Date Issued
March 29, 2012
Type
Doctoral Thesis
Abstract
This PhD thesis dealt with the study of yeast lysis during bottle-fermented sparkling wines ageing
in presence of a β-glucanase oenological preparation. A four-step experimental procedure was set
up: 1) Preliminary study of Lallzyme MMX® oenological preparation, commonly used to improve
wines maturing on lees, both in presence and in absence of two secondary fermentation yeast
strains: Saccharomyces cerevisiae BCS103® and Saccharomyces cerevisiae Lalvin EC1118®, in
dependence of pH and ethanol concentrations, kinetic parameters determination; 2) Bottlefermented
sparkling wines production using the same yeast strains and Lallzyme MMX®; 3) Base
wine and sparkling wines study of: yeasts morphological changes by Transmission Electron
Microscopy and Scanning Electron Microscopy; foaming properties; free amino acids; total
proteins. A sensory analysis and a PCA bi-plot were also performed 12 months after tirage.
Results showed that the optimum pH for b-glucanase was 5.00, but at wine pH (3.20), it exhibited a
satisfactory activity. A lytic activity on yeast cell wall glucans was pointed out, in particular for
EC1118 strain. Ethanol inhibition did not compromise the lytic activity of β-glucanase. TEM and
SEM observations were useful to describe yeast lysis during sparkling wines ageing. Free amino
acids content showed the effect of enzymatic treatment on yeast lysis. Total proteins content
confirmed that autolysis occurred already 8 months after tirage, even if this parameter had no
influences on foaming properties, which decreased during ageing. Sensory analysis showed no
significant differences between samples. Future perspectives may look at increase knowledge about
enzyme inhibitors both in synthetic buffers and in wine.
Additional information
Dottorato di ricerca in Biotecnologia degli alimenti
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